Atomic, Molecular and Optical Physics Commons^™

Harmonic Generation Spectroscopy With A Two-Colour Laser Field Having Orthogonal Linear Polarizations, T. S. Sarantseva, M. V. Frolov, N. L. Manakov, M. Yu. Ivanov, Anthony F. Starace

Anthony F. Starace Publications

The interpretation of many high-order harmonic generation (HHG) experiments is based on the assumption that the HHG yield of an atom can be factorized into (i) a laser-dependent ‘electron wave packet’ with rather simple properties, including a nearly universal shape, and (ii) an atomic photorecombination cross section. We show that this factorization is restricted to linearly polarized laser fields and fails in two-colour laser fields with orthogonal polarizations. At the same time, we show how two-colour HHG spectroscopy using orthogonally polarized intense fundamental and relatively weak second harmonic fields makes a complete experiment possible that enables the retrieval of the …

Imaging Molecular Structures With Atomic Force Microscopy, Unurbat Erdenemunkh, Tyler Flanagan

Student Works

As part of the LEEP project we repaired the Atomic Force Microscopy (AFM), and wrote a user manual on using AFM. Then we scanned Self Assembly of Copolymer Films collaboration with Prof. Sergio Granados –Focil and Copper Oxide Nanocubes with Professor Prof.Luis Smith.

Dynamics Underlying The Gaussian Distribution Of The Classical Harmonic Oscillator In Zero-Point Radiation, Wayne Cheng-Wei Huang, Herman Batelaan

Department of Physics and Astronomy: Faculty Publications

Stochastic electrodynamics (SED) predicts a Gaussian probability distribution for a classical harmonic oscillator in the vacuum field. This probability distribution is identical to that of the ground state quantum harmonic oscillator. Thus, the Heisenberg minimum uncertainty relation is recovered in SED. To understand the dynamics that give rise to the uncertainty relation and the Gaussian probability distribution, we perform a numerical simulation and follow the motion of the oscillator. The dynamical information obtained through the simulation provides insight to the connection between the classic double-peak probability distribution and the Gaussian probability distribution. A main objective for SED research is to …

Measurement Of A Weak Transition Moment Using Coherent Control, Dionysios Antypas

Open Access Dissertations

We have developed a two-pathway Coherent Control technique for measurements of weak optical transition moments. We demonstrate this technique through a measurement of the transition moment of the highly-forbidden magnetic dipole transition between the 6s²S_1/21/2 and 7s²S_1/21/2 states in atomic Cesium. The experimental principle is based on a two-pathway excitation, using two phase-coherent laser fields, a fundamental field at 1079 nm and its second harmonic at 539.5 nm. The IR field induces a strong two-photon transition, while the 539.5 nm field drives a pair of weak one-photon transitions: a Stark-induced transition of …

Experimental Studies Of Lirb: Spectroscopy And Ultracold Molecule Formation By Photoassociation, Sourav Dutta

Open Access Dissertations

Heteronuclear polar molecules have recently attracted enormous attention owing to their ground state having a large electric dipole moment. The long range anisotropic dipole-dipole interaction in such systems is the basis for a variety of applications including quantum computing, precision measurements, ultracold chemistry and quantum simulations. Heteronuclear bi-alkali molecules, only a small subset of polar molecules, have received special attention mainly because the constituent alkali atoms are easy to laser cool and can be relatively easily associated to form molecules at ultracold temperatures. Our choice, the LiRb molecule, is motivated by the relatively high dipole moment (4.1 Debye) of the …

Applicability Of Continuum Fracture Mechanics In Atomistic Systems, Shao-Huan Cheng

Open Access Dissertations

By quantitating the amplitude of the unbounded stress, the continuum fracture mechanics defines the stress intensity factor K to characterize the stress and displacement fields in the vicinity of the crack tip, thereby developing the relation between the stress singularity and surface energy (energy release rate G). This G-K relation, assigning physical meaning to the stress intensity factor, makes these two fracture parameters widely used in predicting the onset of crack propagation. However, due to the discrete nature of the atomistic structures without stress singularity, there might be discrepancy between the failure prediction and the reality of nanostructured materials. Defining …

On The Origin Of Mode- And Bond-Selectivity In Vibrationally Mediated Reactions On Surfaces, Daniel Killelea, Arthur L. Utz

Chemistry: Faculty Publications and Other Works

The experimental observations of vibrational mode- and bond-selective chemistry at the gas–surface interface indicate that energy redistribution within the reaction complex is not statistical on the timescale of reaction. Such behavior is a key prerequisite for efforts to use selective vibrational excitation to control chemistry at the technologically important gas–surface interface. This paper outlines a framework for understanding the origin of non-statistical reactivity on surfaces. The model focuses on the kinetic competition between intramolecular vibrational energy redistribution (IVR) within the reaction complex, which in the long-time limit leads to statistical behavior, and quenching, scattering, or desorption processes that restrict the …

Wave Function For Time-Dependent Harmonically Confined Electrons In A Time-Dependent Electric Field, Yu-Qi Li, Xiao-Yin Pan, Viraht Sahni

Publications and Research

The many-body wave function of a system of interacting particles confined by a time-dependent harmonic potential and perturbed by a time-dependent spatially homogeneous electric field is derived via the Feynman path-integral method. The wave function is comprised of a phase factor times the solution to the unperturbed time-dependent Schrödinger equation with the latter being translated by a time-dependent value that satisfies the classical driven equation of motion. The wave function reduces to that of the Harmonic Potential Theorem wave function for the case of the time-independent harmonic confining potential.

Ground State Of The Singly Ionized Oxygen Vacancy In Rutile Tio2, A. T. Brant, Nancy C. Giles, Shan Yang (杨山), M. A. R. Sarker, S. Watauchi, M. Nagao, I. Tanaka, D. A. Tryk, A. Manivannan, Larry E. Halliburton

Faculty Publications

Results from electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) experiments are used to establish the model for the ground state of the singly ionized oxygen vacancy in the interior of bulk rutile TiO₂ crystals. Hyperfine from ⁴⁷Ti and ⁴⁹Ti nuclei show that the unpaired electron in this S = 1/2 defect is localized on one titanium ion adjacent to the oxygen vacancy (i.e., the spin is not shared by two titanium ions). These defects are formed at low temperature (∼35 K) in as-grown oxidized crystals when sub-band-gap 442 nm laser light converts doubly ionized nonparamagnetic …

Dynamic Electron Control Using Light And Nanostructure, Wayne Cheng-Wei Huang

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The advent of nano-technology has made possible the manipulation of electron or light through nanostructures. For example, a nano-tip in near-field optical microscopy allows imaging beyond the diffraction limit, and a nano-fabricated hologram is used to produce electron vortex beam. While most schemes of electron control utilize only static components, dynamic electron beam control using both light and nanostructures has not yet been realized. In this dissertation, we explore this possibility and study the interplay between electron, light, and nanostructures. A understanding of such a system may facilitate dynamic electron beam control or even bring new insights to fundamental quantum …

Use Of Zwitterionic Molecules For Forming A Hole Or Electron Transport Layer, Bernard Doudin, Pierre Braunstein, Lucie Routaboul, Guillaume Dalmas, Zhengzheng Zhang, Peter Dowben

Peter Dowben Publications

The invention relates to the use of zwitterionic molecules for forming a hole or electron transport layer. The preferred zwitterionic molecules of the invention are derivatives of p-benzoquinonemonoimines. The invention is useful in the field of electronic devices in particular.

The Standard New Astronomy Cryostat For Sofia: A Design For Cryogen-Free Infrared Astronomy, Carey F. Scott, Jeffrey Van Cleve, Eric Burgh, Earl T. Daley, Ali Kashani, Zaheer Ali

STAR Program Research Presentations

Astronomy at infrared wavelengths requires optical instruments that operate at low temperatures, which is typically done using liquid cryogens such as nitrogen and helium. These cryogens are costly and limit the operational time of the science instrument. The Standard New Astronomy Cryostat for SOFIA (SNACS) will provide a design for a helium cryocooler-cooled cryostat that meets the stringent airworthiness requirements of the Stratospheric Observatory for Infrared Astronomy (SOFIA) and can be used by future instrument builders to reduce the cost and risk of their instrument design and development. The SNACS dewar will provide approximately 3.4 x 10^-1 cubic meters …

Optical And Thermal Properties Of Spinel With Revised (Increased) Absorption At 4 To 5 Μm Wavelengths And Comparison With Sapphire, Daniel C. Harris, Giorgio Turri

Publications

Infrared absorption of high-quality, commercial, polycrystalline MgAl2O4 spinel is ∼40% greater in the range of 3.8 to 5.0 μm than the value predicted by the computer code OPTIMATR®, which has been used for window and dome design for more than 20 years. As a result, spinel and a-plane sapphire windows designed to support the same external pressure with the same probability of survival have approximately the same infrared absorptance in the range 3.8 to 5.0 μm. c-Plane sapphire has greater absorptance than spinel in the range 3.8 to 5.0 μm. Spinel has two weak absorption bands near 1.8 and 3.0 …

Breaking Peroxy Bonds In H20 Ice Doped With H202 To Create Positive Hole Charge Carriers., Corey C. Stockburger

STAR Program Research Presentations

Using stress-activated electric conductivity in water ice doped with hydrogen peroxide as a model for stress-activated electric conductivity of igneous and high-grade metamorphic rocks due to the presence of peroxy defects, which when broken, createpositive-hole charge carriers. Blocks of pure H2O ice and H2O2–doped H2O ices, frozen at –20°C, will be stressed with piezo electric transducers(pzt) at one end to generate stress-activated electric currents flowing down the stress gradient. Pure H2O ice should produce no current or a small insignificant amount during rapid deformation or fracture. Stressing H2O2-doped H2O ices, however, should lead to 100-1000 times higher currents. These stress-activated …

Electron Matter Optics Of The Aharonov–Bohm And Stern–Gerlach Effects, Scot Mcgregor

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Since the advent of quantum mechanics and the idea that massive particles exhibit wave properties, physicists have made efforts to make use of the short deBroglie wave length of matter waves for fundamental as well as practical studies. Among these are the precise measurements allowed by interference, diffraction, and microscopy as well as the study of more fundamental aspects of quantum theory such as the Aharonov-Bohm effects or the Stern-Gerlach effect, which are described below. However, in order to use matter waves to observe any of these effects it is necessary to produce and maintain coherence in the waves which …

Pinhole Neutral Atom Microscopy, Philip James Witham

Dissertations and Theses

This work presents a new form of microscopy, the instrument constructed to demonstrate it, the images produced and the image contrast mechanisms seen for the first time. Some of its future scientific potential is described and finally, recent work towards advancing the method is discussed.

Many forms of microscopy exist, each with unique advantages. Of several broad categories that they could be grouped into, those that use particle beams have proven very generally useful for micro and nano-scale imaging, including Scanning Electron, Transmission Electron, and Ion Beam microscopes. These have the disadvantage, however, of implanting electric charges into the sample, …

Vpt2+K Spectroscopic Constants And Matrix Elements Of The Transformed Vibrational Hamiltonian Of A Polyatomic Molecule With Resonances Using Van Vleck Perturbation Theory, Andreana M. Rosnik, William F. Polik

Faculty Publications

Vibrational levels of polyatomic molecules are analysed with Van Vleck perturbation theory to connect experimental energy levels to computed molecular potential energy surfaces. Vibrational matrix elements are calculated from a quartic potential function via second-order Van Vleck perturbation theory, a procedure that treats both weak and strong interactions among vibrational states by approximately block-diagonalising the vibrational Hamiltonian. A clear and complete derivation of anharmonic and resonance constants as well as general expressions for both on- and off-diagonal matrix elements of the transformed Hamiltonian is presented. The equations are written in partial fraction form and as a constant multiplied by a …

Crystallographic Image Processing With Unambiguous 2d Bravais Lattice Identification On The Basis Of A Geometric Akaike Information Criterion, Taylor Thomas Bilyeu

Dissertations and Theses

Crystallographic image processing (CIP) is a technique first used to aid in the structure determination of periodic organic complexes imaged with a high-resolution transmission electron microscope (TEM). The technique has subsequently been utilized for TEM images of inorganic crystals, scanning TEM images, and even scanning probe microscope (SPM) images of two-dimensional periodic arrays. We have written software specialized for use on such SPM images. A key step in the CIP process requires that an experimental image be classified as one of only 17 possible mathematical plane symmetry groups. The current methods used for making this symmetry determination are not entirely …

Well-Posedness Of Characteristic Evolution In Bondi Coordinates, Maria Babiuc-Hamilton, Jeff Winicour

Physics Faculty Research

Gravitational waves carry information about their source, and their detection will uncover facets of our universe, otherwise invisible. Recently, we made publicly available a waveform computation tool, the PITT code, as part of the Einstein Toolkit open software for relativistic astrophysics. The code implements the “characteristic method,” which computes the gravitational waves infinitely far from their source in terms of compactified light cones. We proved that our code produces waveforms that satisfy the demands of next generation detectors. However, the main problem is that the well-posedness of the Einstein equations in characteristic formulation is not proven. Here we present …

Computational Renormalization Scheme For Quantum Field Theories, Rainer Grobe, Qichang Su, R E. Wagner

Faculty publications – Physics

We propose an alternative technique for numerically renormalizing quantum field theories based on their Hamiltonian formulation. This method is nonperturbative in nature and, therefore, exact to all orders. It does not require any correlation functions or Feynman diagrams. We illustrate this method for a model Yukawa-like theory describing the interaction of electrons and positrons with model photons in one spatial dimension. We show that, after mass renormalization of the fermionic and bosonic single-particle states, all other states in the Fock space have finite energies, which are independent of the momentum cutoff.